Milo g



(No Model.)

M. Gr. KELLOGG.

MULTIPLE SWITOHBOARD.

No. 592,344. Patented Oot. 26,1897.

r 'mams mus au, rrgovoum.. wumnmm n. c.

IlNiiTnD STATES PATENT OFFICE.

MILO G. KELLOGG, OF CHICAGO, ILLINOIS, ASSIGNOR TO rlIIE KELLOGG SVITCIIBOARD AND SUPPLY COMPANY, OF SAME PLACE.

lVI ULTIPLE SWITCHBOARD.

SPECIFICATION forming part of Letters Patent N 0. 592,344, dated October 26, 1897.

Application tiled December 21, 1889. Serial No. 334,522. (No model.)

To all whom t r11/ay concern:

Be it known that I, MILO G. KELLOGG, of Chicago, in the county of Cook and State of Illinois, temporarily residing at Stuttgart, in the Empire of Germany, have invented certain new and useful Improvements in Multiple Switchboards for Telephone-EXchanges, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to tele phone-exchan ge systems in which the lines are single-circuit lines or metallic-circuit lines, or in which the two lines are combined in one exchange; and it consists in a system of switching and testing with such lin es, which I shall describe and claim.

I place as many boards inthe central office as are found necessary or desirable in order to properly answer the calls and make the necessary connections and disconnections. On each board is a springjack or similar switch for each line. Each switch has a contact-spring which normally bears on an insulated contact-point and has a contact-piece in sulated from the rest (except by the circuit connections) and is adapted to receive aloopswitch plug and, when a plug is inserted, to disconnect the spring from the contact-point and connect the two contact-pieces of the plug with the spring and with said switch contact-piece, respectively.

The lines of the exchange, whether single or metallic-circuit lines, pass successively through the pairs of contactpoints of their switches on the several boards. The lines then unite into a common wire in which is aV rheotome. W'hen the lines are switched for conversation, they are disconnected from this common wire. Test receiving instruments at each board are connected to the other side of the rheotome and are adapted to be brought for testing into connection with the several lines whether the lines are switched or not. The test receiving instruments and the rheotome and its common wire are disconnected from the ground at the central ofhce.

In the accompanying drawings, illustrating my invention, Figures l:L and lb represent sections of two multiple switchboards of the eX- chan ge to which the same lines are connected. Fig. 2 shows a diagram of the boards with the line connections and apparatus necessary to illustrate myinvention. Fig. 3 shows an operators cord system to be used with the boards.

In the drawings like parts and apparatus are indicated by the same letters of reference.

In Fig. 2, A is a sectional View of the switchboard shown in Fig. l, and A is a sectional viewof the switchboard shown in Fig. 1b, cach as indicated by the line d e.

In Fig. 2, g g represent the springs of the switches, 7L h the contact-points on which the springs normally bear, and j 7' the insulated contact-pieces of the switches. Z l are the switch-holes. a l) are the rubber strips on which the contact-pieces are mounted, as shown, and through the fronts of which are the holes l l. The insulated contact-piecesj j of the switches are so placed that a test-plug or similar device may readily be applied to them-- Vhen a switch-plug (shown in Fig. 3) is inserted into a switch-hole Z, it separates the pieces g 7L of the switch, and one of the contact-pieces of the plug is in contact with the piece j, and the other piece is in contact with the spring g. The switches for the single-circuit lines are marked S", and those for the metallic-circuit lines are marked S.

R is a rheotome or mechanical circuitbreaker containing a clockwork-movement actuated by a spring. It contains an oscillating bar fixed to the verge-shaft and standing at right angles to it. A pair of contactpoints is connected with the bar or with the shaft in such a way that their contact is alternately made and broken with the oscillations. The pair of contact-points are properly insulated and are connected into the circuit, as indicated, for the rheotome. Instead of the rheotome shown any form of mechanical or electrical rheotome or any apparatus which changes the electrical condition of the line, s0 that the change will be indicated on the test receiving instruments, may be connected into the circuit` as indicated, for the rheotome.

Two lines are shown in Fig. 2, one a metallic-circuit line, the two sides or branches of which are marked line No. l and line No. l, respectively, and one a single-circuit line IOO (to be grounded at its outer end) marked line No. 2.

The circuit of the single-circ uit line is as follows: from the subscribers ground, through his station apparatus, through the line and the pairs of contact-points g h, successively, of its switches on the several boards, going in each case to the point h Iirst and thence to the common wire of the lines in which is the rheotome. All the contact-piecesj j of a singlecircuit line are connected together and to their line between its switches and the subscribers station. Y

The circuit of a metallic-circuit line is as follows: One side or branch of the line-say line No. l, as shown-is connected with all the contact-pieces j 7' of its switches on the boards. The other branch ot' the line, say line No. l", passes successively through the pairs of contact-points g 7L of its switches on the several boards, going in each case to the spring first. It then passes to the common wire, in which is the rheotome.

t t are test receiving instruments, one at each board. This test receiving instrument should be of such a character that it will respond to variations in the strength of the testcurrent. As an operators telephone is eX- tremelysensitive to such variations, it is preferably used in connection with this system.

T T are test-plugs, one for each instrument, each connected by a flexible cord to one side of its instrument and adapt-ed to be brought for testing into connection with any contactpiece j at its board. The other side of each test receiving instrument is connected to said common wire of the lines, in which is the rheotome. The connection of the test receiving instruments to said common wire must be on the other side of the rheotome from that to which the lines are normally connected.

B B are test-batteries. There should be a test-battery in the circuit between the place where the lines are united with said common wire and any test-plug. The battery may be placed in the common wire between the place where the lines unite with it and the place where the test-instrum ent circuits branch off from the common wire. In that case only one battery would be required for the exchange.

In the operators cord system shown in Fig. 3, D I) are two loop-plugs, the two contact-points of which are connected by double iexible cords to their loop-switch, clearingout annunciator, and the operators telephone and calli11g-generator,substantially as shown. Only one pair of plugs, with their cords and apparatus, is shown; but other pairs may be added in a way which will be apparent to those skilled in the art. One of the contactpieces of each of the loop-switch plugs is connected by a iiexible conductor to a lever of the looping-in switch, and the two other contact-pieces ofy the plugs are connected together by means of a iiexible cord-circuit. One pair of the plug-bolts are connected together through a clearing-out annunciator.

Another pair are connected together through the operators telephone, and the third pair are connected together through the calling generator or battery.

Each operator has a cord system, and it is conveniently mounted and arranged for her work. This cord system does not require specific description, on account of the fact that any of the usual systems may be adapted to this exchange. The essential feature is that when a line is switched for use it shall be cut off from the rheotome.

I will not explain in detail the operation of the operators cord system in connection with the switchboards, as its operation will be apparent to those skilled in the art. It will be seen that when a line is switched with another line by the insertion of switch-plugs into their switches they are disconnected from the common wire c, in which is the rheotome. When a line is tested by placing a test-plug in a contact-piece j of the line, and

' the line is not switched at any board, there is a complete circuit from the common wire through the test receiving instrument over the line by way of the subscribers station, in the case of a metallic-circuit line, to the pairs of switch contact-points of the line. The rheotome and the common wire and battery are in this circuit, and the test receiving instrument will sound or respond to the Vibrations ot the rheotome, indicating to the operator that the line is free to be connected to. Should, however, the line be switched at any board, this circuit is open and the instrument will not sound or respond. When the instrument, on a test being made, does not respond, Vthe operator knows, therefore, that the line is switched for use and she will not then connect it 'with another line.

I have not shown or described any subscribers calling system. An independent calling-circuit common to many subscribers stations, such as the Law or American district systems, may be used in connection with the test system above described.

I claim as my invention and desire to secure by Letters Patenty l. A test-circuit for a metallic-circuit line, from one side or branch of the line, through the circuit of the line and then to a pair of switch contact-points normally in contact but open while the line is switched by the switch which controls them, thence by an all-metallic connection to a wire common to the lines and through said common wire to a testwire containing a-test receiving instrument and battery, a rheotome in said common wire and a test plug or device in which said testwire terminates, adapted to be brought into connection with said side or branch ofl the line, substantially as set forth.

2. A test-circuit for a metallic-circuit line, from one side or branch of the line, through the circuit of the line and then to a pair of switch contact-points normally closed but open while the line is switched by a switch IOO which controls them to a wire common to the lines, thence by an all-metallic connection to a test-wire connected to said common wire and containing a test receiving' instrument, a rheotome in said common wire and a test plug or device in which said test-wire termi nates, adapted to be brought for testing into connection with said side or branch of the line, and a battery in the circuit between said pair of contact-points and said test-plug, substantially as set forth.

3. A test-circuit for a metallic-circuit line disconnected from the ground at the central oiiiee, from one side or branch of the line through the circuit of the line and pairs of contact-points, one pair on each of several boards, to a wire common to the lines, thence to a test-wire, containing a test receiving instrument, said test-wire being connected to said common wire and terminating in a test plug or device adapted to be brought for testing into connection with said side or branch of the line, a rheotome in said common wire and a test-battery between the place wherev the lines are united with said common wire and said test-plug substantially as set forth.

4. A test-circuit for a telephone-line disconnected from the ground at the central ofiice, from one side of a test receiving instrument, through the instrument to a test plug or device, -thence when the test is applied to the line, thence through a pair of switch contactpoints normally in contact but open while the line is switched by a switch which controls them, to a wire common to the lines, thence, to said side of the test receivinginstrument, a rheotome in said common wire, a battery in the circuit between the place where the lines are united to said common wire and said test-plug, substantially as set forth.

5. A test-circuit for a telephoneline disconnected from the ground at the central oftice, through pairs of contact-points normally in the circuit of the line, one pair on each of several boards, to a wire common to the lines, thence in multiple or parallel circuit to testwires, one for each board, branching off from said common wire, each containing a test receiving' instrument and terminating in a test plug or device adapted to be brought for testing into connection with the line before the line passes to said pairs of contact-points, a rheotome in the circuit `of said common wire between the lines and said test-wires and battery in circuit between the place where the lines are connected to said common wire and any test-plug, substantially as set forth.

(i. A test-circuit for a telephone-line disconnected from the ground at the central ofiice, through a pair of switch contact-points in the circuit of the line normally closed but open while the line is switched by a switch which controls them, to a wire common to the lines, thence in multiple or parallel circuit to test-wires, one for each of several boards, each test-wire containing a test receiving instrument and terminating in a test plug or device adapted to be brought for testing into connection with said line before the line passes to said pair of contact-points, a rheotome in the circuit of the common wire between said lines and said test-wires and battery in the circuit thereby established, substantially as set forth.

v7. In a telephone-exchange system, a metallic-circuit line ungrounded at the central office, one side or branch of which normally passes, successively, through pairs of switch contact-points, one pair on each of several boards and each pair normally in contact but open while the line is switched at their board, and thence connected through a wire co1nmon to the lines to one side of a test receiving instrument, in combination with a test plug or device connected to the other side of said instrument and adapted to be brought for testing into connection with the other side of the line, a rheotome in said common wire and a battery in the circuit between said contact-points and said test-plug, substantially as set forth.

8. In a telephone-exchange system, a line ungrounded at the central office and which normally passes, successively, through pairs of switch contact-points, one pair on cach of several boards, each pair normally closed but open while the line is switched at their board and thence through a wire common to the lines to one side of each of several test receiving instruments, one at each of the boards in combination with test plugs or devices, one

l foreach of the instruments connected to it on the other side and adapted to be brought for testing into connection with the line, a rheotome in the circuit of the common wire and a battery in circuit between said contactpoints and any test-plug, substantially as set forth.

9. ln a telephonelexchange system, a line ungrounded at the central oilice and normally connected through a wire common to the lines to each of several test receiving instruments, one at cach of several boards, in combination with switching devices to disconnect the line from its normal connection with one side of said instruments when the line is switched for conversation, test plugs or devices connected to the other side of the instruments one plug to each instrument and adapted to be brought for testing into connection. with the line whether the line is switched or not, a rheotome in said common wire and a battery in circuit between the points where said normal connection may be broken and any test-plug, substantially as set forth.

10. In a telephone-exchange system, multiple switchboards, metallic circuit line, switches for said line, one switch on each board for said line, each switch containing a pair of contact-points normally in contact but separated while the line is switched at their board and a third contact-piece insulated from the rest (except by the curcuit connections), one branch of the line passing, suc- IOO IIO

cessively, through the pairs of contact-points of its switches and thence to a Wire common to the lines, and the other branch of which is connected to said third contact-pieces of its switches, in combination With test-Wires, one for each board, each branching off from said common Wire, containing a test receiving inn strument at its board and terminating ina test plug or device adapted to be brought for testing into connection With any of said third contact-pieces at its board, a rheotome in said common Wire before said test-Wires branch off from it and a battery in the testcircuit thereby established, substantially as set forth.

11. In a telephone-exchange system, multiple switchboards, telephonedines ungrounded at the central office, switches for said lines, one switch for each line on `each of the boards, each switch having a pair of contactpoints normally in contact but open While its line is switched at their board, each line ypassing normally through said pairs of contactpoints of its switches and uniting With a Wire common to the lines, in combinationl with test receiving instruments, one at each board each connected on one side to said common Wire and on its other side to a test plug or device adapted to be brought for testing into connection with any line Whether the line is switched or not, a rheotome in said common Wire and battery in any testcircuit established on testing substantially as set forth.

In Witness whereof I hereunto subscribe my name this 29th day of November, 1889.

MILO G. KELLOGG. Vitnesses:

EMIL ABENHEIM, MARGARETHA RIEHL. 

